ISU researchers study concrete as alternative for wind turbines

An Iowa State University graduate student and an engineering professor are studying whether concrete can be a suitable alternative to steel for the construction of wind turbines.

An Iowa State University graduate student and an engineering professor are studying whether concrete can be a suitable alternative to steel for the construction of wind turbines.

Grant Schmitz, an ISU graduate student of civil, construction and environmental engineering, and Sri Sritharan, an ISU engineering professor and leader of the College of Engineering’s Wind Energy Initiative, are trying to determine if using assembled concrete towers would be a practical way to raise wind turbines from the common height of 80 meters to the steadier winds of 100 meters and taller.

“We have definitely reached the limits of steel towers,” Sritharan said. “Increasing the steel tower by 20 meters will require significant cost increases and thus the wind energy industry is starting to say, ‘Why don’t we go to concrete?’”

Sritharan and Schmitz worked with Doug Wood, an engineering specialist at Iowa State’s Structural Engineering Research Laboratory to test the load placed on a full-size test segment of a 100-meter concrete wind turbine.

The engineers wanted to see if the segments could handle 150,000 pounds of load, 20 percent over the extreme load at that height.

All three versions of the test segments withstood 150,000 pounds of lateral load.

“Panel cracking was expected at very high loads and will be closed upon removal of the load,” Sritharan said. “This can also be avoided if this is requested by the industry.”

After all the testing, Schmitz said, “I definitely think we’re getting close to being able to use this technology in the industry.”

Concrete can offer several advantages over steel, including extending the life of the tower, easier transportation and greater access to materials, less reliance on imported steel, and design versatility.

“What we have shown is that this system can potentially be deployed to a 100-meter height for a 2.5 to 3 megawatt system,” Sritharan said.

“A lot of people are talking about taller, concrete wind turbine towers,” he said. “And we’ve already established a new versatile concept with multiple construction options.”